Patent GB-856625-A (GB)
Title: Improvements relating to change-speed gearing
IPC: F16D21/04
Filed: 1957-01-21
Abstract: 856,625. Retractive switches; electromagnetic switches. GETRAG GETRIEBE-UND ZAHNBADFABRIK G.m.b.H. Jan. 21, 1957 [Jan. 21, 1956; March 6, 1956; March 17, 1956; April 30, 1956 (2)], No. 2211/57. Class 38 (5). [Also in Groups XXIV and XXXV] Relates to an electromagnetically controlled changespeed gear (see Group XXIV). A switch for controlling a four-speed change-speed gear comprises a lever 602, Figs. 12 . . . 14, in electrical contact with a surrounding casing 605 through a spring 604, and biased upwardly within the casing by a compression spring 607. A block of insulating material 611 contains four contacts 603 engaged alternatively by a conducting plate 601 when the lever 602 is rocked. The switch is described as controlling a four-speed gear in which the speeds are selected by energization of one or other of solenoids I . . . IV, Fig. 14, to attract an armature 628, Fig. 16, on the end of a selector rod 626. On the selector rod 626 are mounted contact strips 614 . . . 617 (see also Fig. 18), co-operating with sliding contacts 618, Fig. 17, each in series with one of the solenoids. The contact strips 614 . . . 617, &c. are used in co-operation with a separate neutral return switch 608, Fig. 12, to move the selector rod 626 to a position where its clutch-operating wedge head 625 is between the first and second speed gears 623, 622 and all the gears are free on their shaft 624. If the gearing is in its fourth speed position, with the selector rod 626 in its extreme left-hand position in Fig. 16, depression of the neutral switch 608 energizes the contact 617. This is in electrical contact with the other contact strips 614 . . . 616, so that the part of the contact strip 614 now in contact with its associated sliding contact 618 is simultaneously energized. This causes the solenoid III to be energized, thus attracting the armature 628 which moves to the right of Fig. 16. As the selector rod 626 moves rightwards, the contact 615 slides under its contact 618 and energizes the solenoid II. Immediately afterwards, the sliding movement of the selector rod 626 is in such a position that its wedge head 625 lies approximately between the planes of the two gears 622, 623, all the contacts 618 are out of engagement with the sliding contacts 614 . . . 617. Should inertia cause the selector rod 626 to move to the right, the sliding contact 615 engages its associated contact 618 to re-energize the solenoid II, which tends to draw the armature 628 back to the left. Similarly, should the selector rod 626 tend to drift to the left, the sliding contact 616 engages with its associated contact 618 to energize the solenoid I, to pull the selector rod back to the right. In order to increase the effective effort of the solenoids I . . . IV and begin movement of the selector rod 626, the armature 628 is formed as a hollow sleeve containing a compression spring 627 through which movement of the armature sleeve is transmitted to the selector rod. On energizing one of the solenoids, the armature sleeve moves to compress the spring 627, and thus stores energy which further movement of the armature sleeve increases to a sufficient extent to de-clutch the engaged gear.